Economizer



Nov.` 18,v 1930. w. F. 'KEENANHJR 1382105 EcoNMIzER Filed April 17, 1929 s sheets-shet 1 o o o o O O 0 0 o o o o o o o o o o o o o o O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O 0 o o o OOOO NVENTOR ATTORNEY Nov. 18, 1930. w. F. KEENAN, JR I 1382205 EcoNoMIzER Filed April 17, 1929` 3 Sheets-Sheet 2 ATT RNEY Nov. 18, 1930. w. F. KEENAN, JR 1382305 ECONOMIZER med April 17, 1929 s sheets-sheet s A INVENTOR 5a Mhz/y ATToRNgY Patented Nov. ls, 193o UNITED sTATEs PATENT OFFICE WALTER F. KEENAN, JR., OF PELEAM lyfANOR, NEW YORK, ASSIGNOR 'I'O FOSTER WHEELER CORI'ORATION, OIE` NEW YORK, N. Y., A CORPORATION OF NEW' YORK EcoNoMIzEn Application filed April 17,

My invention relates to economizers, especially economizers of the type wherein feed water is heated by products of combustion for use in a` steam boiler.

The primary object of my invention is to provide economizers, and particularly economizers of the gill ring or extended surface type, with a larger cross-Sectional area of flow in the part where steam may be generated than in the part where only sensible heat, that is, heat of the liquid, is added while providing an economizer of simple construction, of minimum floor space requirements and of efiicient heat transfer.

In carrying out the invention, I prefer to use a gas passage of` oblong cross-section across which extend groups of transversely equally spaced tubes, tubes of one group extending transversely of the passage in the direction of greater dimension and tubes of another group extending transversely of the passage in the direction of lesser dimension with the groups connected in series.

Further objects of the invention and the nature thereof and a preferred manner of carrying the same into effect will be described in connection with the'accompanying drawings forming a part of this specification and of which:

Fig. 1 is a cross-Sectional view of a part of a steam boiler and an economizer or feed water heater arranged to supply feed water. to theflboiler;

Fig. 2 is a cross-Sectional view taken on the line 2-2 of Fig. 1; 1

Fig.. 3 is a cross-Sectional view taken on the line 3-'3 of Fig. o1; and

Fig. 4 is a cross-Sectional view taken on the line 4-4 'of Fig. 1.

Reference character 10 designates a steam boiler which may be of any of various types. The boiler has a steam and water drum 11.

` Products of combustion leave the boiler by way of flue gas passage or flue.12 which extends horizontally away from the boiler setting and then downwardly, the products of combustion passing to the ybottom 13 of the flue and thence to a stack.

. will' presently appear.

1929,'` Serial No. 355,815.

in providing this shape of transverse section In the form illustrated the flue cross-section has a greater dimension, more than twice as greatas the lesser dimension; that is, the wall 14 is'more than twice as wide as wall v15.

In the lower part of the vertical portion of flue 12 is a first group of tubes 16 comprising a plurality of banks of relatively closely spaced tubes extending transversely of the flue in the direction of greater dimension of the'oblong transverse cross-section. The tubes of the lowermost bank are connected to an inlet manifold 17 supplied With feed water from a feed pump. Individual tubes Vof each bank of tubes are connected to individual tubes of the next adjacent bank so that water flows in parallel through the tubes of any one bank and in series through thebanks. The tubes are connected by return bend members 18. The tubes of any one bank are staggered with respect to the tubes of the adj acent bank.

The tubes are made of steel tubing surrounded by members 19 of cast iron forming a greatly extended surface for flue gas contact due-to the flanges or gillsfor fins extending outwardly from the tubes proper.

The uppermost return bends 18a of this first group of tubes are connectedl to bent tubes 20 formed with right angle bends and of`diferent sizes. These tubes 20 connect to a manifold 21 arranged outside the flue and extending in the direction of greater dimension of the oblong cross-section. The general direction of flow of water is altered 90 by passing through tubes 20. Tubes 20 are connected to manifold 21 at equally spaced points so as to distribute' the water evcnly into the manifold. The manifold is open .inside so that /the separate parallel streams of water here unite.

Above the group cof tubes 16 is a second group of tubes 22 extending transversely of the flue in the direction of lesser dimension of the oblong transverse section, that is, at right angles to the tubes of the first group 16. This group of tubes also comprises a plurality of banks of tubes connected similarly to the tubes of group 16 by separate return bends 23 connecting individual tubes of a bank with` individual tubes of an adj acent bank. The tubes of this second group are also staggered and gilled.

The tubes of the two groups are transversely equally spaced. This provides many more tubes per bank in the second. group 22 thany in the first group 16.

The tubes of the lowermost bank of the tubes of the second group 22 are connected to manifold 21 so that'water fiows from manifold 21 in parallel through the tubes of a bank in the second group. Thus manifold 17 serves to subdivide the flow and manifold 21 to further subdivide the flow. The tubes of the two groups are of the same size.

The uppermost return bends 23a of the second group are connected to tubes 24 Which, in turn, are connected to drum 11 of the boiler 10 at equallyspaced distances, thus evenly distributing the water to the drum.-

The first group of tubes may be considered as serving merely to heat Water and the second group to heat Water and form some steam.

In the past economizershave usually been i designed to heat feed Water through a range of 150 degrees F. or less from' an inlet temperature of 200 degrees F. or less. Under such conditions no steam would be formed in the economizer with pressures ordinarily used in boiler plants where economizers are installed. In recent years, however, there has been a tendency to increase the amountV of work done in economizers. lFactors contributing to this condition have been, increase of feed water temperatures entering economizers to from 300 to 4z00 degrees F. due tol regenerative stage heating of feed water in turbine plants, and .the operation of high pressure boilers at high ratings resulting in mcreased gas temperatures entering economi'zers. It is, therefore, not unusual at the present time to have cases where it isldesirable to develop an appreciable amount of steam in economizers. it is necessary to provide for the release of such steam into the boiler without objectionable increase of pressure loss through economizers. i

It is well known that when water becomes steam it expands greatly. Consequently, with a uniform flow through an economizer, the increase in volume causes an increased speed of flow'of fluid. I-Iowever, if the rate of flow of water is such as to give efficient transfer and the best size, the friction arising from. the expansion is likely to be excessive. Consequently it is advisable to increase the cross-Sectional area of flow through the steaming section.

It is characteristic of the 'extended surface or -gill type economizer that the crossySectional area for flow is less than in bare or straight tube economizersfV With this type yigreaaoe In order to do this.

of economizer a greater increase of flow through the steaming section is advisable than with bare tube economizers. While the heat absorption per lineal foot is greater with the gill type economizer, and consequently the length of travel through the steaming section shorter, other things being equal, the loss due to friction (pressure loss) increases as the velocity of flow increases and with increased velocity the presi sure loss is greater in the gill type economizer even with the decreased travel.

By the arrangement above described, T have greatly increased the area of Iflow through the steaming section (by more than twice) while maintaining a compact arrangement. The tubes being equally spaced `and of equal size the cross-Sectional area of flow is proportional to the number of; tubes in a bank. With an oblong cross-section of flue and with the groups at right angles to each other, the number of tubes per bank and consequently the cross-Sectional area of flow of one group relative. to the other is Proportional to the relative dimensions of the oblong cross-sections. a

By using theV curved tubes 20, I change thedirection of flow without complicating.

the arrangement, without exposing pipes and with relatively inexpensive construction.

As shown in the drawings,-T use more 1. An economizer for heating boiler feed :1

water by means df products of combustion comprising a flue having an oblong crosssection, a first group 'of tubes extending transversely of the flue in the direction of greater dimension, a -second group of tubes y extending transversely' of the flue in the direction of lesser dimension, the cross-sectional area of flow of the second 'group being greater than the cross-Sectional area of flow of the first group, and connections for passing fluid through the groups ofjtubes in series.

2. An economizer for heating boiler feed water by means of products of combustion comprising a flue` having *an oblong crosssection, a first group ofI tubes extending transversely of the'flueiin the direction of greater dimensiomaI second group of tubes extending transver'sely of the flue in the direction of lesser dimension, the cross-secfrom the spiritk V tional area of flow of the lsecond group be- 1,7sa2o5 ,extending transversely of the flue in` the direction of lesser dimension, the cross-secing greater than the cross-sectional area of floW of the first group, and a manifold eX- tending in said direction of greater dimension to which the tubes of both groups are connected.

4. An economizer for heating boiler feed Water by,means of products of combustion comprising a fiue having an oblong crosssection, a first group of tubes extending transversely of the flue in the direction Iof 'greater dimension, a second group of tubes extending transversely' of the flue in the direction of lesser dimension, the cross-sectional area of fiow' of the second group .being greater than the cross-Sectional area of "flow of the first group, and a manifold outside the ```flue and adjacent thereto and eX- tending in said direction of greater dimension to which the tubes of both groups are connected.

5. 'An economizer for ,heating boiler feed Water by means of products of combustion comprising a flue having an oblong cross-section, a first group of tubes extending transversely of the flue in the direction of greater dimension and forming a relatively long path of fioW for Water of relatively small Sectional area, fins onsaid tubes, a second -group of tubes extendingtransversely of the f flue in the direction of lesser dimension and forming a relatively short path of floW for tion, a first. group of tubes extending trans- 'versely of the flue in the direction of.greater ldimension and forming a relatively long path of floW for water of relatively small cross- Sectional area, fins on-said tubes, a second group of tubes extending transversely of the flue in the direction of lesser dimension and' forming a relatively short path of flow for Water of relatively large cross-.Sectional area,

-fins on the last-mentionedktubes and means for conducting water first through the first group and thence through the second group comprising a manifold extending in sald direction of greater dimension to which the tubes of. both groups are connected.

' 7. An economizer for heating feed water by means of products of combustion compris- .ing a fiuehaving an oblong cross-section, a

first group of tubes extending transversely of the flue in the direction of greater dimension and forming a relatively long path of flow forfwater of relatvely small cross-sectional area, a second group of tubes extend- \ing .transversely of the flue in the direction of lesser dimension and forming a relativel)r short path of floW for Water of relatively large cross-Sectional area, the tubes being spaced Asubstantiallv equal distances apart transversely in both groups and means for conducting Water first through the first group and thence throughA the second group comprising a manifold extending in said direction of greater dimension to Which the tubes of both groups are connected.

8. An economizer for heating boiler feed Water by means of products of combustion comprsing a flue having an oblong cross-section, a plurality of series connected banks of tubes forming a first group of tubes extendng transversely of the flue in the direction -of greater dimension, a plurality of series connected banks of tubes forming a second group of tubes eXtending transversely of the flue in the direction of lesser dimension, the tubes being spaced'substantia/.lly equal dis-- tances apart transversely in both groups of tubes and the cross-Sectional area of floW of the second group being greater than the crosssectional area of floW of the first group, and means for conducting 'Water first through the first group and thence through the second .group comprising a manifold extending in the direction of greater dimension to Which the tubes of both groups are connected.

9. An economizer comprising a flue having an oblong cross-section, a plurality of series connected banks of tubes forming a first group of tubes extending transversely'of the flue in the direction of greater dimension, fins on said tubes, a plurality of series connected banks of tubesqforming, a second group of tubes extending,transverse1y of the flue in the direction of lesser dimension, fins on the last mentioned tubes, the tubes being spaced substantia'lly equal distances apart transversely in both groups of tubes and a manifold extending in the direction of greater dimension .to Which the tubes of both groups are connected.

10. An economizer for heating boiler feed A steaming section, said long tube elements havmg a 1esser cross-Sectional, area of flow for Water than the shorter tube elements, and meansV to 'conduct Water first through said long elements and thence through said shortp er elements.

11. An economizer for heating boiler feed Water by means of products ofcombustion comprising a flue having an oblong crosssection, a first group of' tubes extending transversely of the flue inthey direction of greater dimension and forming a relatively long path of flow for Water of relatively smalllcross-sectional area, a' second group of tubes extending transversely of theflue in the direction of lesser dimension and forming a relatively short path of flow for Water of relatiyely large cross-Sectional area, the

tubes belng spaced substantially equal distances apart transversely in both groups,

means for conducting Water first through the first group and thence through the second group comprising a manifold eX-tending in said direction of greater dimension to Which the tubesof both-groups are connected, and said groups being arranged in said flue so that the products of combustion first contact the second group and then contact the first group.

12. An economizer for heating boiler feed Water by means of products'of combustion comprising a flue having an oblong crosssection, a plurality of series-connected banks of tubes extending transversely of the flue in the direction of greater dimension, fins von said tubes, a plurality of series-connected banks of tubes forming a second group of tubes extending transversely of the flue in the direction of lesser dimension, xins on the last mentioned tubes7 the` tubes being placed substantially equal, distances apart transversely in both groups of tubes, a manifold extending in the direction of greater dimension to Which the tubes of both groups are connected, and the groups being arranged in the flue so that the products of combustion first contact. the second group and then cont'act the first group. A

13. An economizer for heating boiler feed Water by means of products of combustion comprising a flue having an oblongcross-- section, a first group of tubes extending transverselyof the flue in the direction of greater dimension, a second group of tubes extending transversely of the flue in the direction of lesser dimension, the cross-Sectional area of flow ofthe second' group being greater than the cross-Sectional area of flow of the first group, Connections for passing fluidthrough the groups of tubes in series, and the groupsbeingl arranged in the flue Whereby .the products of combustion first contact the 'second group and thenontact the first group.

In testimony whereof I` have hereunto alfixed my signature.

WALTER F. KEENAN, JR.

weaaot 

